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General properties. Name, symbolxenon, Xe. Pronunciation. It is a colorless, dense, odorless noble gas found in the Earth's atmosphere in trace amounts. More than 4. 0 unstable xenon isotopes undergo radioactive decay, and the isotope ratios of xenon are an important tool for studying the early history of the Solar System. They found xenon in the residue left over from evaporating components of liquid air. This led him to the invention of the xenon flash lamp in which light is generated by passing brief electric current through a tube filled with xenon gas.

In 1. 93. 4, Edgerton was able to generate flashes as brief as one microsecond with this method. He tested the effects of varying the breathing mixtures on his subjects, and discovered that this caused the divers to perceive a change in depth. From his results, he deduced that xenon gas could serve as an anesthetic. Although Russian toxicologist Nikolay V. Lazarev apparently studied xenon anesthesia in 1. American medical researcher John H. Lawrence, who experimented on mice.

Xenon was first used as a surgical anesthetic in 1. American anesthesiologist Stuart C.

Cullen, who successfully used it with two patients. However, while teaching at the University of British Columbia, Neil Bartlett discovered that the gas platinum hexafluoride (Pt. F6) was a powerful oxidizing agent that could oxidize oxygen gas (O2) to form dioxygenyl hexafluoroplatinate (O2+.

On March 2. 3, 1. The program, called IBM in atoms, used a scanning tunneling microscope to arrange 3.

It was the first time atoms had been precisely positioned on a flat surface. At standard temperature and pressure, pure xenon gas has a density of 5. Earth's atmosphere at sea level, 1. It can dissolve hydrocarbons, biological molecules, and even water. It is completely metallic at 1.

GPa. When metallized, xenon looks sky blue because it absorbs red light and transmits other visible frequencies. Such behavior is unusual for a metal and is explained by the relatively small width of the electron bands in that state. Many solids have lattice constants smaller than solid Xe.

This results in compression of the implanted Xe to pressures that may be sufficient for its liquefaction or solidification. It is inert to most common chemical reactions (such as combustion, for example) because the outer valence shell contains eight electrons. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound.

Xenon emits a band of emission lines that span the visual spectrum. After this separation, generally performed by fractional distillation in a double- column plant, the liquid oxygen produced will contain small quantities of krypton and xenon. By additional fractional distillation, the liquid oxygen may be enriched to contain 0.

Finally, the krypton/xenon mixture may be separated into krypton and xenon by further distillation. The abundance of xenon in the atmosphere of planet Jupiter is unusually high, about 2. Sun. Elements more massive than iron- 5. This is more than any other element except tin, which has ten. The longest lived of these isotopes is 1. Xe, which undergoes double beta decay with a half- life of 2.

Xe, 1. 33. Xe, 1. Xe, and 1. 35. Xe are some of the fission products of 2.

U and 2. 39. Pu. The nuclear spins can be aligned beyond ordinary polarization levels by means of circularly polarized light and rubidium vapor. Such non- equilibrium alignment of spins is a temporary condition, and is called hyperpolarization.

The process of hyperpolarizing the xenon is called optical pumping (although the process is different from pumping a laser). Spin polarization of 1. Xe can persist from several seconds for xenon atoms dissolved in blood.

Xe has a huge cross section for thermal neutrons, 2. This was discovered in the earliest nuclear reactors built by the American Manhattan Project for plutonium production. Fortunately the designers had made provisions in the design to increase the reactor's reactivity (the number of neutrons per fission that go on to fission other atoms of nuclear fuel). The iodine- xenon method of dating gives the time elapsed between nucleosynthesis and the condensation of a solid object from the solar nebula.

In 1. 96. 0, physicist John H. Reynolds discovered that certain meteorites contained an isotopic anomaly in the form of an overabundance of xenon- 1. He inferred that this was a decay product of radioactive iodine- 1. This isotope is produced slowly by cosmic ray spallation and nuclear fission, but is produced in quantity only in supernova explosions.

Because the half- life of 1. I is comparatively short on a cosmological time scale (1. I. These two events (supernova and solidification of gas cloud) were inferred to have happened during the early history of the Solar System, because the 1. I isotope was likely generated shortly before the Solar System was formed, seeding the solar gas cloud with isotopes from a second source. This supernova source may also have caused collapse of the solar gas cloud. Since this isotope is generated by radioactive decay, the result may indicate that Mars lost most of its primordial atmosphere, possibly within the first 1. Almost all known xenon compounds contain the electronegative atoms fluorine or oxygen.

Xe. F is theorized to be unstable. The green, paramagnetic Xe+2 is formed by the reduction of Xe.

F2 by xenon gas. More than 3. Xenon dichloride, formed by the high- frequency irradiation of a mixture of xenon, fluorine, and silicon or carbon tetrachloride. However, Xe. Cl. 2 may be merely a van der Waals molecule of weakly bound Xe atoms and Cl. Its crystal structure may allow it to replace silicon in silicate minerals.

These unstable salts easily disproportionate into xenon gas and perxenate salts, containing the Xe. O4. Xe. OF2 is formed by reacting OF2 with xenon gas at low temperatures.

It may also be obtained by partial hydrolysis of Xe. F4. It disproportionates at . The latter reaction also produces a small amount of Xe. O3. F2. Xe. OF4 reacts with Cs. F to form the Xe.

OF. The latter is synthesized from dioxygenyl tetrafluoroborate, O2. BF4, at . One example is xenon hydrate (Xe. The xenon atom trapped in the fullerene can be observed by 1. Xe nuclear magnetic resonance (NMR) spectroscopy. Through the sensitive chemical shift of the xenon atom to its environment, chemical reactions on the fullerene molecule can be analyzed. These observations are not without caveat, however, because the xenon atom has an electronic influence on the reactivity of the fullerene. When xenon atoms becomes energized, however, they can form an excimer (excited dimer) until the electrons return to the ground state.

This entity is formed because the xenon atom tends to complete the outermost electronic shell by adding an electron from a neighboring xenon atom. The typical lifetime of a xenon excimer is 1.

That is, the chromaticity of these lamps closely approximates a heated black body radiator at the temperature of the Sun. First introduced in the 1. They are an excellent source of short wavelength ultraviolet radiation and have intense emissions in the near infrared used in some night vision systems. Xenon is used as a starter gas in HID automotive headlights, and high- end .

The interaction of this plasma with the electrodes generates ultraviolet photons, which then excite the phosphor coating on the front of the display. It has the lowest thermal conductivity and lowest ionization potential of all the non- radioactive noble gases. As a noble gas, it does not interfere with the chemical reactions occurring in the operating lamp. The low thermal conductivity minimizes thermal losses in the lamp while in the operating state, and the low ionization potential causes the breakdown voltage of the gas to be relatively low in the cold state, which allows the lamp to be more easily started.

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